As shown in FIG. 47, in a related-art sewing machine, a needle thread J runs out of a thread roll 98 wound around a needle thread bobbin and reaches a thread take-up lever 12a via a pretension component 96, a tension disc 95, a rotary tension component 94, and a tension spring (generally called a “high tension spring”) 93 and subsequently a sewing needle 12ba. 
The related-art sewing machine is also configured as shown in FIG. 48. A needle bar case 2314 that slides in a horizontal direction with respect to an arm 2312 has a needle bar case main body 2330 equipped with the thread take-up levers 12a, needle bars 12b, the tension springs 93, and others; and a needle thread adjustment member mounting section 2340 fixedly put on an upper surface of the needle bar case main body 2330. The needle thread adjustment member mounting section 2340 is equipped with the tension discs 95 and the rotary tension components 94 for adjusting tension of respective needle threads. Needle thread guides 1300 are placed above the respective tension discs 95, and needle thread guides 1302 are placed beneath the respective rotary tension components 94.
The related-art sewing machine is also equipped with a machine sewing thread feeding device described in connection with Patent Document 1. In relation to the machine sewing thread feeding device described in connection with Patent Document 1, the thread feeding device has a needle thread downstream gripper, an upper looper thread downstream gripper, and a lower looper thread downstream gripper. The needle thread downstream gripper grips a needle thread guided from a needle thread upstream gripper; the upper looper thread downstream gripper grips an upper looper thread guided from an upper looper thread upstream gripper; and the lower looper thread downstream gripper grips a lower looper thread guided from a lower looper thread upstream gripper. At the time of formation of a stitch, the needle thread downstream gripper is opened, whereupon the needle thread is drawn from the needle thread downstream gripper by a stitch forming device. During cloth feeding, the needle thread downstream gripper is closed. Similarly, at the time of formation of a stitch, the upper looper thread downstream gripper is opened, whereupon an upper looper thread is drawn from the upper looper thread downstream gripper by the stitch forming device. During cloth feeding, the upper looper thread downstream gripper is likewise closed. Moreover, at the time of formation of a stitch, the lower looper thread downstream gripper is also opened, whereupon a lower looper thread is drawn from the lower looper thread downstream gripper by the stitch forming device. During cloth feeding, the lower looper thread downstream gripper is closed. During feeding of a cloth, the upstream grippers are opened, and the downstream grippers are closed. A draw-in member moves while drawing a thread, thereby piling up the thread. On the contrary, during formation of a stitch, the upstream grippers are closed, and the downstream grippers are opened, the draw-in member moves to a position where the member does not draw the thread, and the thread is released.
The present applicants also filed the embroidery sewing machine described in connection with Patent Document 2.